\input pstfig
$
\setcoorunit{4}{1}
\psset{xunit=0.4\psyunit}
%\drawaxes{-2.6}{5}{-3}{3.2}
\drawaxes{-2.8}{2.8}{-1.4}{1.75}
\markylabel{-1}{\raise 2pt\hbox{$-\pi$}}{-1pt}
\markylabel{-0.5}{\raise -1.3em\hbox{$-\!\nfrac{\pi}{2}$}}{-1pt}
\markxlabel{0}{\scriptstyle O}{1em}
\markylabel{0.5}{\raise -8pt\hbox{$\nfrac{\pi}{2}$}}{0ex}
\markylabel{1}{\raise 2pt\hbox{$\pi$}}{1pt}
%\markylabel{-1}{\raise 2pt\hbox{$\scriptstyle-\pi$}}{0em}
%\markylabel{-0.5}{\raise -8pt\hbox{$\scriptstyle-\!\frac{\scriptstyle\pi}{\scriptstyle2}$}}{0ex}
%\markxlabel{0}{\scriptstyle O}{1em}
%\markylabel{0.5}{\scriptstyle\frac{\scriptstyle\pi}{\scriptstyle2}}{0ex}
%\markylabel{1}{\raise 2pt\hbox{$\scriptstyle\pi$}}{1pt}
\psplot{-1}{1}{asin(x)/\pinum}
\thinline
\psplot{-1}{1}{1-asin(x)/\pinum}
\psplot{-1}{0.8}{-1-asin(x)/\pinum}
\dashline
\psline(-1, -1.33)(-1, 1.52)
\psline( 1, -1.33)( 1, 1.52)
\psline(-1, -0.5 )( 0, -0.5)
$
\bye
